Viruses of Diarrhea Flashcards

1
Q

4 Grops of Viruses that are important causes of GI diseases:

A
  1. Rotaviruses
  2. Calicivirus
  3. Astroviruses
  4. Adenoviruses
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2
Q

Rotavirus

A
  • Rotavirus genus of the Reoviridae family
  • ( + ) ds RNA icosohedral naked segmented
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3
Q

Rotavirus Structure

A
  • lsmall, spherical, 65-75 nm in diameter, (wheel-shaped)
  • 11 segments of double stranded RNA
  • double capsid (inner and outer shells),
  • outer capsid, VP4 and VP7, target for neutralizing antibodies
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4
Q

Rotavirus Replication

A
  • replicates in the cytoplasm
  • virus release by host cell lysis
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5
Q

Rotavirus Clinical Disease

A
  • Rotavirus infections are common during cooler months among infants and young children 1 to 24 months of age
  • The virus primarily localizes in the duodenum and proximal jejunum causing destruction of villous epithelial cells
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6
Q

Rotavirus Incubation

A

•1-3 days

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7
Q

Rotavirus Symptoms

A
  • Abrupt onset, vomiting followed by diarrhea (copious, watery, brown stools), life-threatening in malnourished or an immunodeficient, normal duration of diarrhea 5-8 days
  • In severe cases, the stools may be clear; referred as hakuri, the “white stool diarrhea.”
  • Viral excretion usually lasts 2 to 12 days
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8
Q

Rotavirus Immune Response

A
  • Rotavirus infection responds with type-specific humoral antibodies that probably does not last for a lifetime after the first infection.
  • Recovery from the first infection provides 38% protection against infection, 77% protection against diarrhea, and 87% protection against severe diarrhea.
  • Subsequent infections give long-term immunity.
  • Type-specific IgA antibodies are produced in the intestinal tract, correlate best with immunity.
  • Breastfeeding also seems to play a protective role against rotavirus disease in young infants.
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9
Q

Rotavirus Diagnosis

A
  • Detect virus in stool
  • RIA, ELISA, EM, PCR
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10
Q

Rotavirus Treatment

A
  • No specific treatment
  • Use of fluids and electrolytes is needed in severe cases and can be life saving.
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11
Q

Rotavirus Prevention

A
  • Highly infectious and can spread quickly in family and institutional settings.
  • Control consists of rigorous hygienic measures: hand washing and disposal of enteric excretions.
  • Live oral vaccine given in 3 doses, first at 6-12 weeks and 2nd and 3rd doses at 4-10 weeks interval
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12
Q

Norwalk like Viruses

A
  • Norwalk like Viruses - Norovirus and Sapovirus genera of the Caliciviridae family
  • ( + ) ss RNA icosohedral naked
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13
Q

Norovirus Structure

A

•Round, small ss (+) RNA particles, naked capsid (27-38nm), 2 capsid proteins; Vp1 and VP2, replicate in the cytoplasm like positive sense RNA virus, assembly in the cytoplasm and release upon cell lysis

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14
Q

Norovirus (Calicivirus) Epidemiology

A

•Norovirus the leading cause of viral gastroenteritis in children following rotavirus vaccine

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15
Q

Norovirus (Calicivirus) Symptoms

A

•1-2 day incubation, abrupt onset, vomiting and diarrhea, normal duration 1-2 days, seen in older children and adults, no enterotoxic features

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16
Q

Norovirus (Calicivirus) Diagnosis

A

•not usually done, PCR, RIA, EM

17
Q

Astrovirus Structure

A
  • Astrovirus genus of the Astroviridae family
  • star-shaped
  • ( + ) ss RNA icosohedral naked
  • no cell culture
18
Q

Astrovirus Transmission

A

•fecal oral

19
Q

Astrovirus Incubation

A

•1-2 days

20
Q

Astrovirus Symptoms

A
  • site of infection is intestine
  • primarily infect infants and children, outbreaks in school children and elderly nursing home residents
21
Q

Astrovirus Diagnosis

A

•PCR, EM

22
Q

Adenovirus

A
  • ds DNA naked
  • fecal-oral transmission
  • small intestine site of infection
  • 8-10 days incubation period
  • viral gastroenteritis associated with specific serotypes (40 and 41)
  • primarily a disease of young children, replicate in intestine and excreted in stool
23
Q

Other Viruses of Diarrhea

A
  • Coronaviruses (Torovirus)
  • Coxsackie (immunocompromised hosts)